GB 2,030,981 discloses and claims a process for preparing 1,1,1,2-tetrafluoroethane which comprises reacting 1,1,1-trifluorochloroethane with hydrogen fluoride in molar excess at a temperature not lower than 300.degree. C. in the presence of an inorganic chromium (III) compound with the introduction of from 0.002 to 0.05 mole of oxygen per mole of 1,1,1-trifluorochloroethane into the reaction system. The patent also states that a high conversion of 1,1,1-trifluorochloroethane to 1,1,1,2-tetrafluoroethane is achieved by reacting 1,1,1-trifluorochloroethane with a large excess of hydrogen fluoride at a relatively high temperature in the presence of an inorganic chromium (III) compound. In this process, deterioration of the catalyst is prevented by adding 0.002 to 0.05 mole of oxygen per mole of 1,1,1-trifluorochloroethane. When the oxygen content is below the lower limit, unsatisfactory catalyst deterioration occurs. When the oxygen content is more than the upper limit, catalyst deterioration is not a problem but the selective conversion to 1,1,1,2-tetrafluoroethane decreases. It is believed that this decrease in selectivity occurs because the catalyst promotes the oxidation of hydrogen chloride to molecular chlorine and water. [See Chemical Week, Page 18, June 24, 1987 for the use of chromium based catalysts for the oxidation of hydrochloric acid to chlorine and water.] Chlorine in the presence of HF reacts with the CF.sub.3 CH.sub.2 Cl to produce CF.sub.3 CHClF which in turn can react with starting material or product. This reaction with chlorine results in a significant yield loss of the desired product CF.sub.3 CH.sub.2 F. In addition, the formed water in combination with HF is very corrosive.
U.S. Pat. No. 2,744,148 discloses an alumina catalyst which may be promoted with a metal (chromium, cobalt, nickel, copper and palladium) and a process for fluorinating haloalkanes to highly fluorinated products. A process is disclosed which activates the catalyst and converts at least part of the alumina to basic aluminum fluorides.
U.S. Pat. No. 2,744,147 discloses a alumina catalyst which may be promoted with a metal (cobalt, nickel and chromium) and a process using the catalyst in a fluidized bed for fluorinating haloalkanes using the catalyst at a temperature between 180.degree. to 425.degree. C.
It is an object of this invention to provide a catalyst which will retain activity over a prolonged period of time in the presence of oxygen including high concentrations of oxygen [&gt;0.05 mole per mole of 1,1,1-trifluorochloroethane] while minimizing the oxidation of hydrogen chloride to chlorine and water.